Add about a thousand female Costco employees to the 1.5 million Wal-Mart women who are going to feel the impact of the Supreme Court's ruling on class action discrimination suits this week. Of course, the parties disagree on how much of a dealbreaker the Wal-Mart decision will be for the Costco case.

Both cases are (or were) class-action gender discrimination lawsuits against big box retailers accusing them of barring women employees from promotions. They shared the same lead counsel, Brad Seligman.

The Costco group sued in 2004, saying that women were being kept out of the assistant general manager and general manager positions, and they were certified as a class in 2007. Costco appealed, but the court decided to wait and see what the Supreme Court would say about Wal-Mart.

One law professor told Bloomberg, "Bottom line: Under Dukes, a class cannot be certified for this case as framed. If I were Costco, I would be feeling pretty good about this decision."

Seligman, of course, disagrees. He now says that Costco is a different case, because it's much smaller and only pertains to only two rungs of management, whereas the Wal-Mart case operated at multiple levels. Also, though the Supreme Court questioned how Wal-Mart corporate brass could sanction discrimination when its operations were so decentralized, at Costco, the CEO signs off on every single store manager promotion. But that'll ultimately be up to the Ninth Circuit.